Since the overall width of a BB30 BB is 68mm including the bearings, and the BB30 crank spindles are made to work with that, I don't understand how those external cups would work. The spindle will be much too short, no? What am I missing?

_________________There's sometimes a buggy.How many drivers does a buggy have?

One.

So let's just say I'm drivin' this buggy...and if you fix your attitude you can ride along with me.

You should be able to use a Sram S900, Rotor 3D+, or the newer BB386 cranks with those BSA to BB30 adapters as these cranks have wider spindles. Someone here has successfully used the Sram S900 cranks. You cannot make it work with Red, Force, or other 'standard' BB30 cranks. There are some other threads discussing this same topic.

That was my understanding too. So, their description "The T30 allows you to use your BB30 cranks on a standard BSA Frame. " is somewhat misleading? Are they not disclosing that you can use a BB30 crank IF you have a longer spindle?

Their descriptions makes it sound like you can use a standard BB30 crank (ie. RED, FORCE) on a 68mm BSA frame. I understand that the Rotor 3D+ and "386" cranks have a longer spindle.

Certain crank manufacturers call their cranks BB30 when they are not. They are just standard cranks with 30mm spindles. There is more to BB30 than just the 30 mm spindle, so yes it is misleading. Basically imo they want to jump on the BB30 bandwagon without having to invest the capitol to build a BB30 crank, so they accomplish this by slapping on a 30mm spindle and pass it off as the Real McCoy to less savvy customers.

Sorry about the rant but I think it's really confusing, unnecessary, and misleading to market a crank as BB30 just because it can fit in a BB30 BB shell...what crank can't?

As far as those cups go who knows maybe the seller or manufacturere doesn't know any better.

All I'll say is that one of us is right and one of us is wrong. Buy that BB and you'll see. If nothing else do yourself a favor before you buy it and, ask if they'll cover the return shipping costs when you have to return it, because it's not compatible with your crank.

Here is the math: the BSA BB shell ID is 35 mm, Italian is 36 mm. The BB30 axle is - of course - 30 mm. In 5-6 mm you have to fit the bearing and some kind of interface with the threaded shell. The minimum thickness of the latter is 1.5 mm, so you have 3.5-4.5 mm left for the bearings. Needle type bearings might be found in this size, but they will not deal with the side load, so at least 1 ball bearing cartridge/side must be used. There is no standard ball bearing cartridge with these measurement parameters in any manufacturers catalog (30X37 is the closest).

If you're interested in using a powermeter the NEW RED Quarq BB30 crank will work with these cups in your BSA 68mm frame. It is similar in contruction to the S975 but uses the new graphics and chainrings (and quarq). The reason it works is that instead of preloading the bearings with a wavy washer (standard red/force) there is a threaded collar and sleeve. This takes up more room, when removed you have room for the external bb30 cups...just use a wavy washer to preload the bearings.

I think I will try it based on the fact that I can send it back as a warranty claim and they will cover the cost. Worth the try???

Timothy,

Thanks for the reply. Im a little confused. It had always been my understanding a BB30 crank (Red, Force,FSA) could not be adapted to BSA because of the spindle length is too short with the external cups. However, with the added spindle length on cranks like Rotor 3d+ and BB386 cranks, they can use a BSA BB.I want to use a SRAM Red bb30 crank. Just trying to clear up my confusion.

The shell on a BB30 bike is wider than BSA. The cups make up the difference.

I've never installed that exact combination with my own hands but this is the application they were designed for based on factory specs.

I´m doing BB30 conversion as part of my living in my shop so I know a bit about that.

A standard BB30 crankset like RED and others have a too narrow axle to fit a BSA threaded frame + two cups, there´s just not enough place.

The best solution is a modular crankset like Lightning which have spacers on the axle, or a MTB version of Sworks cranks on a road frame, they are wider.I use Cannondale Hollowgram just because they are modular and no way a BSA 68 shell with cups will be at right width for a Hollowgram axle of 104mm, we are talking about use a 131mm axle, a SRM axle at 122 can MAY be used,a 128mm can be used, haven´t tested yet.

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